Here's a good source of information on troubleshooting your RV refrigerator.
RV Refrigerator Videos
Pay close attention to his Heater Elements Part II video. He said he received a batch of bad elements that would work but did not have enough wattage to operate the refrigerator properly. Check out your replacement element before you install it.
The 120 volt heating element in our Sunseeker is accessible from the outside access panel. You don't have to remove the refrigerator to get to it.
The 120 volt heater is visible in Herk's photos, the fourth and fifth from the top. It's the silver rod that goes into the vertical tube on the right. The element has two black wires. Be sure 120 volt power has been off for a while because it can be very hot.